/Engine/Source/Runtime/Engine/Classes/Engine/WorldComposition.h
Returns currently visible and hidden levels based on distance based streaming
void GetDistanceVisibleLevels ( const FVector * InLocations, int32 Num, [TArray](API\Runtime\Core\Containers\TArray)< [FDistanceVisibleLevel](API\Runtime\Engine\Engine\FDistanceVisibleLevel) > & OutVisibleLevels, [TArray](API\Runtime\Core\Containers\TArray)< [FDistanceVisibleLevel](API\Runtime\Engine\Engine\FDistanceVisibleLevel) > & OutHiddenLevels ) const